The present invention relates to a lens apparatus extending and retracting with relative movement of a plurality of lens barrel members in an optical axis direction, and an image-pickup apparatus including the same.
Conventionally, cameras provided with a lens barrel that includes a plurality of optical lenses moving in the optical axis direction to change an image-pickup magnification and to perform focusing have been known.
Such a lens barrel is constituted by a cam ring on which a cam groove is formed and a lens barrel member provided with a cam follower portion engaging with the cam groove (for example, refer to Japanese Patent Application Laid-Open No. 7-27962).
When such a camera is dropped by a user to be crashed onto the ground, a protruding (extending) lens barrel thereof may be damaged. Then, it is necessary that the lens barrel should have a configuration with high impact resistance and high load bearing.
In general, in order to make the lens barrel more solidly configured against an external force, it is necessary to make the lens barrel larger. Accordingly the size of the camera also increases.
In addition, as for the lens barrel disclosed in Japanese Patent Application Laid-Open No. 2001-324663, a flange portion is formed on the cam ring and a receiving portion is formed on a fixed barrel that is contactable with the flange portion.
The lens barrel having such a form described above receives the external force at the receiving portion when the external force is applied thereto, whereby the cam ring does not easily disengage from the fixed barrel.
However, in this form of the lens barrel, positions of the flange portion and a follower pin engaging with the cam groove are different in the optical axis direction, so that the engagement length between the cam ring and the fixed barrel increases. As a result, the thickness (length) of the lens barrel in the optical axis direction increases, thereby increasing the size of the camera.
Thus, Japanese Patent Application Laid-Open No. 2006-106463 proposes a lens barrel whose thickness in the optical axis direction is reduced. In this lens barrel, in addition to the configuration of the lens barrel disclosed in Japanese Patent Application Laid-Open No. 2001-324663, a cam pin and a stopper rib are disposed at the identical position in the optical axis direction, thereby reducing a retracted length of the lens barrel including the cam ring to decrease the thickness of the camera.
However, the lens barrel disclosed in Japanese Patent Application Laid-Open No. 2006-106463 does not have an enough engagement area of the stopper ribs engaging with each other for a normal image-taking position. Consequently, disengagement of the cam ring from the fixed barrel cannot be sufficiently prevented when the external force is applied to the lens barrel.